A pressure detector is a device for detecting the pressure of gas, which is connected to a container with gas to be measured and performs pressure detection, by a sensing unit inside the pressure detector, that detects the pressure of the gas directly flowing from the container to the inside of the pressure detector. However, due to the problem that the gas to be measures dissipates easily through the intervals between the components of the pressure detector, the pressure detector often fails to obtain a correct pressure value. Moreover, the vapor or other corrosive material in the to-be-measured gas may corrode the circuit board inside the pressure detector easily, which leads to damage of the circuit board and less accurate detections, and also leads to a shortened lifetime of the pressure detector.